Toxicity tests. Tests regarding effects of imidacloprid on honey bees | [Essais de toxicité. Essais sur les effets du l'imidaclopride sur les abeilles]
2001
Wallner, K. ((University Stuttgart Hohenheim, Stuttgart (Allemagne). Landesanstalt fuer Bienenkunde))
The hazard of the systemic seed disinfectant, Gaucho WS (a.i. imidacloprid), on bees was examined with the use of Phacelia tanacetifolia in tent and field tests. The substance is suspected to be responsible for the decrease in the crops of sunflower honey. The test criteria included: foraging activity, orientation, mortality in front of the hive entrances, honey sac weight of returning forager bees, the amount of imidacloprid in the honey sac load, in the honey itself, and in the bee bread, the toxic effect on larvae, and the foraging activity on flower clusters in the field. In the tent, the bees (2 colonies with 5 combs) on the disinfected area (120 m2, 0.005 g a.i./m2) showed no symptoms of toxic effects or disorientation. Flight activity (10 observations: 5 min/5 days), honey crop, and the daily mortality (7 days) remained unchanged. The analysis of the honey sac content (40 bees pooled) showed that Phacelia plants excrete traces of this substance with the nectar (3x10 ppb). Imidacloprid was also detectable in the bee bread (3x10 ppb). The attractiveness of disinfected Phacelia did not change under field conditions. A negative influence on honeybees could not be determined
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